Free-flowing, high density, agglomerated riboflavin powders

ABSTRACT

A novel spray-drying technique process, and the resulting composition, for preparing a high density, agglomerated vitamin-containing composition having improved tableting characteristics.

This is a division of application Ser. No. 242,789 filed Apr. 10, 1972,and now abandoned.

BACKGROUND OF THE INVENTION

Spray dried agglomerated and densified products are often essential toprovide free-flowing material having the physical characteristicsnecessary for direct compression tableting technique.

Heretofore, free-flowing powder materials were prepared by dusting driedpowders with a suitable dusting agent to minimize the development ofstatic electricity and thereby prevent sticking and blocking of thepowder flow path. Examples of such dusting agents, which are well-knownin the art, include starch, starch esters and silicic acid.

In addition, agglomeration could be achieved by various wet or drytechniques. For example, wet granulation includes both the rotatingdrum, extrusion techniques and instantizing apparatus.

The formation of free-flowing spray-dried high density agglomeratessuitable for direct compression tablet manufacture was, heretofore, notachieved using spray-drying techniques. Spray-drying depends on rapidevaporation rates which are obtained through a high spraysurface-to-mass ratio (i.e., fine particle-sized materials). However, iflarge particulates and agglomerates of the spray feed are formed duringthe passage through the drying zone, these semi-dried particles tend toadhere on the walls of the spray chamber and thereon accumulate largemasses of a wet product. This is especially true when the spray dropletsformed from vitamin E emulsions formulated with a gelatin base, vitaminB₂ slurry in a film-forming base and vitamin A emulsion prepared ineither acacia or a gelatin base.

It is an object of this invention, therefore, to prepare free-flowing,high density coated agglomerated material suitable for directcompression into tablets using spray-drying techniques.

BRIEF DESCRIPTION OF THE INVENTION

This invention relates to a spray-drying process for preparingfree-flowing high density agglomerates suitable for direct compressioninto tablets. It has been found that the introduction of ultra-fine(i.e., 2-15 microns) particle sized absorbents into the spray chamberleads to the formation of coated high density, free-flowing agglomerateswhich pass through the drying zone without the above describeddeleterious effects of wall adhesion and wet mass accumulationassociated with prior art processes.

DETAILED DESCRIPTION OF THE INVENTION

Free-flowing high density agglomerates suitable for direct compressioninto tablets, prepared by the process of this invention, i.e., theintroduction of ultra-fine particle-sized absorbents into the spraychamber, can be obtained by either of two modifications.

In the first modification the absorbents are metered directly into thespray chamber. The quantity of absorbent metered into the chamber rangesfrom about 1 to about 5% by weight based on the weight of thespray-dried product. The fine particle size absorbent immediately coatsthe semi-dried droplets as well as the chamber wall thus preventingbuildup of material on the chamber wall and the consequent deleteriousformation of large masses of wet product. In addition, the presence ofthe absorbent minimizes the development of static electricity bothduring the spray-drying step and on the resulting dry agglomerates.

In the second modification, a mixture of absorbent and previously fineparticle-sized spray-dried material is directly metered into the spraychamber by a suitable valve arrangement. The mixture is immediatelypicked up by the high velocity air stream from the air disperser in thechamber and is intimately admixed with the atomized wet spray product,thereby forming coated agglomerates which dry readily. This secondmodification results in formation of large dried agglomerates when themetered admixture comprises from about 1 to about 15% by weight of theabsorbent and from about 85 to about 99% by weight of the fineparticle-sized spray-dried product. Examples of the fine particle-sizedspray-dried materials include vitamin E encapsulated in hydrolyzedgelatin, vitamin A encapsulated in hydrolyzed gelatin, vitamin Aencapsulated in gum acacia, vitamin D encapsulated in hydrolyzedgelatin, riboflavin encapsulated in maltrin and spray-dried stabilizedcalcium pantothenate.

The process claimed herein is, of course, limited to formulations whichcan be dried by spray-drying techniques. The preferred materials for usein this process are vitamin slurries or emulsions. Representativeemulsions include vitamin A-hydrolyzed gelatin, riboflavin-maltrin and,in particular, a vitamin E-hydrolyzed gelatin emulsion as described inU.S. Pat. No. 3,608,083. (Ser. No. 734,540).

The preferred embodiment of this invention is the preparation of afree-flowing, high density agglomerated vitamin E product suitable fordirect conpression tableting techniques. Vitamin E comprises a group ofnatural substances known as tocopherols. They are fat soluble, closelyrelated chemical compounds found in vegetable oils such as wheat germoil, rice oil, soy bean oil and the like. α-Tocopherol has the greatestbiological activity per unit weight while its isomers beta, gamma,delta, epsilon, zeta and eta-tocopherols have vitamin E activity to alesser extent. The tocopherols and their esters such as tocopherylacetate, tocopheryl palmitate, tocopheryl succinate and the like arenormally water-insoluble and oily, waxy, or low melting, whichproperties make them unsuitable for certain pharmaceutical applications,particularly, those in which a powder is required, e.g., vitamin tabletsand capsules. Any of these tocopherols, their esters or compoundsconvertible to either tocopherols or their esters are suitable for usein the process of this invention. However, in order to insure thedesired stability of vitamin E activity in the final powder it ispreferred to use tocopherol esters. Typical suitable esters are theacetate, palmitate, succinate and the like. The preferred ester usedaccording to this invention is dl-α-tocopheryl acetate. Sufficienttocopheryl acetate is utilized to insure that the resulting spray-driedpowders contain from about 40 to about 60% by weight of vitamin E, i.e.,the amount of vitamin E activity present in the powder is that whichwould be present if the vitamin E activity is present as pure vitamin E.

The aforesaid tocopheryl esters are emulsified with a hydrolyzed gelatinhaving a 0 Bloom and a molecular weight range of from 9,000 to 11,000.The amount of hydrolyzed gelatin in the final powder generally variesfrom about 60 to about 40% by weight. A hydrolyzed gelatin which isrepresentative of those suitable for use in this invention is, e.g.,marketed by Croda Colloid. While this soluble protein is representativeof the hydrolyzed gelatins useful herein, this invention is, of course,in no way limited to the use of a particular hydrolyzed gelatin.

The tocopheryl ester and hydrolyzed gelatin are emulsified by admixing a45% hot hydrolyzed gelatin stock solution with a warm dl-α-tocopherylacetate. The admixture is then homogenized by the rapid agitation of aHomo mixer. The resulting emulsion, diluted with water to about 45%solids to give a proper spray viscosity, has a particle size range inthe dispersed phase of from below 1 micron to about 3 microns. Inaddition, other vitamin emulsions, i.e., those of vitamins A, B₂, D andvarious admixtures thereof prepared in gelatin or gum acacia bases andsuitable for spray drying, can be used in the process as claimed in thisinvention.

One representative emulsion of vitamin A is constituted of 610 parts byweight of gelatin, 150 parts by weight of sucrose, 40 parts by weight ofEMQ, 200 parts by weight of vitamin A palmitate and water, q.s. to make40-50% solids emulsion.

Another representative example is a riboflavin emulsion constituted of216 parts by weight of riboflavin, 80 parts by weight of oyster shellflour, 104 parts by weight of maltrin and 380 parts by weight of water.

These spray dryable emulsions and slurries can contain optionaladditives as may be desired. For example, since hydrolyzed gelatinsolutions readily support microbiological growth, it is preferred to addpreservatives to protect the emulsion during preparation and holdingprior to spray drying. The preservatives are added to the water used toprepare the gelatin solutions so that a level of about 0.4 to about0.6%, preferably about 0.5%, of, for example, sodium benzoate and about0.15 to about 0.25%, preferably about 0.2%, of, for example, sorbicacid, result in a final 45% by weight hydrolyzed gelatin solution.

Of critical importance in the process claimed in this invention is theintroduction of ultra-fine absorbents (i.e., glidants) into the spraychamber. These absorbents or glidants are, in the main, silicic acid,silicon dioxide or various silicates. However, materials other thanthese may be equally effective since it is not so much the chemicalcompositions of the absorbents but rather their physical propertieswhich are critical to this process. To be effective, the absorbent mustbe substantially insoluble in cold water, resistant to wetting by water,have an appreciable capacity to absorb and/or adsorb water and oil(i.e., an oil absorption capacity of from about 150 to about 400 poundsper 100 pounds), free-flowing, do not develop static electricity, have aparticle size range from about 2 microns to about 16 microns and have asurface area of from about 175 to about 360m² /gm. Suitable materialsinclude silicic acid, silicas, alkali metal silicates, magnesiumcarbonate, kaolin clays, dicalcium phosphate, tricalcium phosphate andthe like. Representative commercial materials include Syloid, Cab-O-Sil,Aerosil, Supernat, Santocel, Zealox and Polysilicic acid. The preferredmaterial for the process of this invention is silicic acid, a white,amorphous powder, insoluble in water and having the emperical formulaSiO₂.x H₂ O.

Another critical factor in the process is the feed rate of the emulsionor slurry. In the usual spray-drying operation, the emulsion feed is soregulated as to form small particles which dry before hitting the wallsof the dryer chamber. These small particles have poor tabletingcharacteristics, however. By increasing the feed flow, i.e., flooding,larger particles can be formed. These particles, which are not driedbefore striking the walls of the dryer chamber, adhere on the walls andbuild up as a semi-solid plastic mass, a condition known as ringing.However, when a absorbent or glidant is added to the drying chamber,operation under flooding conditions produces the desired large particleswhich are then coated with absorbent, agglomerate and and dry. There isno wall adhesion and a free-flowing high-density, large particle-sizeproduct results.

In the process of this invention, an emulsion is spray dried using astandard Spray Drying Apparatus. Inlet and outlet temperatures areadjusted to an optimum and the emulsion is fed at a high feed ratethrough the atomizer into the Dryer Chamber. The absorbent is thenmetered into the chamber through a top inlet valve positioned above anatomizer wheel rotating at a fixed rpm. The flow rate of absorbent isadjusted to achieve a concentration of from about 1 to about 5% byweight based on the weight of the spray-dried product. As soon as thedrying system is balanced, the atomizer wheel speed and the outlettemperature are lowered by increasing the feed rate of the emulsion overthe atomizer wheel causing a flooding condition. These adjustments causethe atomized spray droplets to increase in size, remain in athermoplastic state longer, agglomerate and densify. The semi-driedagglomerates are prevented from adhering to the drying chamber wall bythe coating of the glidant on both the particle surface and the chamberwall.

The agglomerated vitamin E product prepared by the process of thisinvention can be used in many ways as, for example, directly in foodpremixes, in dry water dispersible preparations as dilutions for bulksales using feed carriers and in the preparation of tablets. The producthas a moisture content range of 1-5% by weight and a bulk density rangeof 25-32 pounds/ft³. A minimum of 95% of the material passes through aNo. 20 U.S. standard sieve. From 75-100% of the particles have particlesizes of from 74 to 287 microns.

The vitamin E product has tableting properties which are essential forthe manufacture of high potency coated and uncoated tablets by a directcompression procedure. Heretofore, such high potency vitamin E tabletswere difficult to manufacture because of poor flow properties, stickingof the powder product to the tablet machine table, variations in tabletweights, soft tablets, laminating of tablets and cracking of coatedtablets.

The following examples illustrate this invention.

EXAMPLE 1

This example illustrates the procedure for the preparation of afree-flowing, high density agglomerated formulation of vitamin E acetatesuitable for direct compression to tablets.

One kilogram of sodium benzoate and 2 kilograms of sorbic acid aredissolved in 547 kilograms of distilled water by heating to 65°-70°C.450 kilograms of hydrolyzed gelatin (Croda Colloid) are then addedslowly with agitation. The agitation is continued for 2 hours with theslurry maintained at 70°-80°C. Agitation is then stopped and thetemperature is maintained at 70°C. overnight to eliminate the air fromthe heavily foamed gelatin solution.

The hot hydrolyzed gelatin stock solution is transferred to ahomogenizing kettle equipped with a Homo-Mixer. Rapid agitation is begunwith the Homo-Mixer and 600 kilograms of dl-α-tocopheryl acetate,previously heated to 40°-50°C., is slowly added. Distilled water isadded at this time if needed to insure proper pumping action of theHomo-Mixer during emulsification.

In operation the primary emulsion is cycled through a sonic homogenizer,e.g., Homo-Mixer, back to the emulsion kettle to check the emulsionmicroscopically for particle size distribution in the dispersed phase.When an emulsion of suitable dispersed particle size, i.e., 1-3 microns,is prepared, the solids concentration is adjusted to insure properviscosity by the addition of sufficient distilled water to make thetotal used 740 kilograms. The emulsion is then passed through the sonichomogenizer into a suitable storage vessel.

The inlet temperature of a 14 foot Bowen Dryer is adjusted to 325°F. andthe outlet temperature adjusted to 200°-210°F. The operation of thespray dryer is started using water. When the system is well balanced,the water is shut off and the vitamin E/hydrolyzed gelatin emulsion isfed to the Dryer. The atomizer wheel speed positioned below theabsorbent inlet is set initially at 12,000-13,500 rpm and the flow rateof silicic acid glidant, metered into the Dryer through a top inletvalve, is adjusted to provide a glidant concentration approximatelyequal to 2-3% of the concentration of the spray-dried product. Theatomizer wheel speed is then adjusted downward to 8,000-9,000 rpm and,after five minutes, the Dryer outlet temperature is adjusted to195°-180°F. By these adjustments, the emulsion feed rate is increasedcausing the spray droplets to increase in size and agglomerate. The wetagglomerate particles are coated with the glidant prior to impinging onthe drying chamber wall. There is no adhesion and thus the thermoplasticparticles have a long drying period.

In operation, it is often necessary to adjust the aforesaid dryingconditions to optimize the physical properties (density, particle sizedistribution) of the agglomerated spray-dried product.

The resulting material is a white, free-flowing powder having a bulkdensity of 25-30 pounds per cubic foot and a moisture content of 1.0-4%by weight.

The agglomerates have the following typical particle-sized distribution:

    U.S. Standard Mesh  % Retained                                                ______________________________________                                        On 60 mesh          14.0-40.0                                                 On 80 mesh          22.0-28.0                                                 On 100 mesh          7.2- 7.0                                                 On 200 mesh         30.4-17.5                                                 Through 200 mesh    26.4- 7.5                                                 ______________________________________                                    

To show the significant improvement achieved by the use of thisfree-flowing, high-density, agglomerated product in comparison tomaterial prepared by the standard spray-drying techniques, the followingvitamin E chewable tablet (200 IV/tablet) and vitamin E sugar coatedtablet (200 IV/tablet) formulations were evaluated using directcompression techniques.

    ______________________________________                                        Formulation (mg./tablet)                                                                    Chewable Sugar Coated                                           ______________________________________                                        Vitamin E acetate, 50%                                                                        400        400                                                spray-dried                                                                   Cocoa           22         --                                                 Silicic Acid    35          50                                                Sugar Tab        311.5     --                                                 ______________________________________                                    

The results are tabulated below:

    A. Chewable Formulations                                                                Standard          Agglomerated                                                Spray-Dried       Spray-Dried                                       ______________________________________                                        Tableting                                                                     Characteristics                                                                         Poor Flow         Good Flow                                                   Laminating of Tablets                                                                           No Lamination                                               Sticking to Machine Table                                                                       No Sticking                                       Tablet Hardness                                                               (Strong Cobb                                                                  Units, SCU)                                                                             Capping to 5      12-24                                             B. Sugar-Coated Formulations                                                            Standard          Agglomerated                                                Spray-Dried       Spray-Dried                                       ______________________________________                                        Tableting                                                                     Characteristics                                                                         Capping           Excellent                                                   Not suitable for tablets                                            Tablet                                                                        Hardness                                                                      (Strong Cobb                                                                  Units, SCU)                                                                             No tablets        20-25                                             ______________________________________                                    

EXAMPLE 2

This example illustrates the procedure for the preparation offree-flowing, high density, agglomerated formulation of an agriculturaldry vitamin A palmitate, potency 325,000 vitamin A units per gram.

610 Kilograms of low Bloom hydrolyzed gelatin are added slowly withagitation to 610 kilograms of distilled water heated to 65°-70°C. Theagitation is continued for 2 hours with the slurry maintained at70°-80°C. Agitation is then stopped and the temperature is maintained at70°C. overnight to eliminate the air from the heavily foamed gelatinsolution.

The hot hydrolyzed gelatin stock solution is transferred to ahomogenizing kettle equipped with a Homo-Mixer. Rapid agitation is begunwith the Homo-Mixer and a mixture of 200 kilograms of vitamin Apalmitate and 40 kilogram EMQ(1,2-dihydroxy-6-ethoxy-2,2,4-trimethylquinoline) previously heated to40°-50°C. is slowly emulsified. 150 kilograms of sucrose are slowlyadded to the emulsion with continued agitation. Distilled water is addedat this time if needed to insure proper pumping action of the Homo-Mixerduring emulsification.

In operation the primary emulsion is cycled through a sonic homogenizerto insure the preparation of an emulsion with suitable dispersedparticle size, i.e., less than 1-3 microns. The solids concentration isadjusted to insure proper viscosity by the addition of sufficientdistilled water to reduce the total solids content of the emulsion to40-45%. The emulsion is then passed through the sonic homogenizer into asuitable storage vessel.

The inlet temperature of a 14 foot Bowen Dryer is adjusted to 400°F. andthe outlet temperature adjusted to 270°-280°F. The operation of thespray dryer is started using water. When the system is well balanced,the water is shut off and the vitamin A-antioxidant-hydrolyzed gelatinemulsion is fed to the Dryer. The atomizer wheel speed positioned belowthe absorbent inlet is set initially at 12,000-13,500 rpm and the flowrate of silicic acid absorbent-glidant, metered into the Dryer through atop inlet valve, is adjusted to provide a glidant concentrationapproximately equal to 2-3% of the concentration of the spray-driedproduct. The atomizer wheel speed is then adjusted downward to8,000-9,000 rpm and after 5 minutes, the Dryer outlet temperature isadjusted to 255°-245°F. By these adjustments, the emulsion feed rate isincreased causing the spray droplets to increase in size andagglomerate. The wet agglomerate particles are coated with the glidantprior to impinging on the dryer chamber wall. There is no adhesion andthus the thermoplastic particles have a longer drying period.

In operation, it is often necessary to adjust the aforesaid dryingconditions to optimize the physical properties (density, particle sizedistribution) of the agglomerated spray-dried product.

The resulting material is a tan, free flowing-powder having a bulkdensity of 35-45 pounds per cubic foot and a moisture content of 1 to 5%by weight.

The agglomerates are free-flowing and have enhanced stability comparedto regular spray-dried powders.

EXAMPLE 3

This example illustrates a procedure for the preparation offree-flowing, high density, agglomerated, non-dusting, static-freeriboflavin, 50% using a slurry as the feed material for the Spray Dryer.

104 Kilograms of Maltrin 15, a hydrolyzed cereal product, are dissolvedin 380 kilograms of water. 80 kilograms of oyster shell flour are thenadded with rapid agitation followed by 216 kilograms of riboflavin. Theresulting slurry has a 51.32% solids content.

The inlet temperature of a 14 foot Bowen Dryer is adjusted to 350°F. andthe outlet temperature adjusted to 225°-235°F. The operation of thespray dryer is started using water. When the system is well balanced,the water is shut off and the riboflavin slurry is fed to the Dryer. Theatomizer wheel speed positioned below the absorbent inlet is setinitially at 12,000-13,500 rpm and the flow rate of silicic acidglidant, metered into the Dryer through a top inlet valve, is adjustedto provide a glidant concentration approximately equal to 2-3% of theconcentration of the spray-dried product. The atomizer wheel speed isthen adjusted downward to 8,000-9,000 rpm and after 5 minutes, the Dryeroutlet temperature is adjusted to 220°-205°F. By these adjustments, theemulsion feed rate is increased causing the spray droplets to increasein size and agglomerate. The wet agglomerate particles are coated withthe glidant prior to impinging on the dryer chamber wall. There is noadhesion and thus the thermoplastic particles have a longer dryingperiod.

In operation, it is often necessary to adjust the aforesaid dryingconditions to optimize the physical properties (density, particle sizedistribution) of the agglomerated spray-dried product.

The resulting material is a brown, free-flowing, non-dusting,static-free powder having a bulk density of 35-36 pounds per cubic footand a moisture content of 4-5% by weight.

The agglomerates are free-flowing and, from the viewpoint of directusage in premix operation are dust-free, and nonstatic with goodparticle size distribution.

EXAMPLE 4

This example illustrates the procedure for the preparation of anagglomerated formulation of dry vitamin E acetate using a mixture ofultrafine absorbent and previously spray-dried material as the absorbentfeed.

A 200 gallon, jacketed Pfaudler kettle is charged with 50 gallons ofdistilled water, 1.75 kilograms of sodium benzoate and 0.7 kilogram ofsorbic acid and heated to 65°-75°C. 153 kilogram of hydrolyzed gelatin(0 Bloom and molecular weight of 7,000-11,000) are slowly added withconstant agitation. 30 kilograms of warm (35°-40°C.) dl-α-tocopherylacetate are slowly added to 50 kilograms of the hydrolyzed gelatinsolution at 50°-60°C. with stirring using a Homo-Rod Mixer untilemulsification is complete. Sufficient distilled water is then added toreach about a 45% solids emulsion which provides a proper sprayingviscosity.

The emulsion is then spray dried using a 14 foot Bowen Dryer with aninlet temperature of about 325°-350°F. and an outlet temperature ofabout 210°-225°F. The resulting product is white, has particles in therange of from about 20 to about 30 microns, a bulk density of about 18.5pounds per cubic foot and a moisture content of about 1%.

This finely spray-dried vitamin E, 50% is intimately mixed with 4-12% ofMicro-Cel C absorbent. Micro-Cel C is calcium silicate having an averageparticle size of 3.4 microns, an oil absorption capacity of 100-300lbs./100 lbs. and a surface area of 175 m² /gram.

Another emulsion, constituted as described in Example 1 above, is thenprepared for spray drying. The 14 foot Bowen Dryer is set up for cyclonecollection. Operation is started using water as the feed with theinitial inlet temperature set at 325°F. and the initial outlettemperature set at 210°F. When the system is balanced, the feed water isreplaced by the vitamin E emulsion. As the same time, the atomizer wheelspeed is adjusted initially to 11,000-13,500 rpm. The top inlet feederis adjusted to permit a flow rate of the admixture of Micro-Cel Cabsorbent and finely spray-dried vitamin E, 50% so as to provide aconcentration approximately equal to 1-2% of the concentration of thespray-dried product. The atomizer wheel speed is adjusted downward to8,000 to 11,000 rpm. After 5 minutes the outlet temperature is alsoadjusted downward to 195°-180°F., thus increasing the feed rate toflooding condition which results in the formation of large particle sizedroplets. These wet atomized particles of vitamin E emulsion collidewith the dried particles of adsorbent and vitamin E/hydrolyzed gelatinto form large agglomerates coated with the adsorbent which are easilydried and collected. The moisture content, bulk density and particlesize range are the same as reported for the agglomerated material inExample 1 above.

EXAMPLE 5

This example illustrates the procedure for the preparation of afree-flowing, high density, agglomerated flavor oil encapsulated powder.

610 Kilograms of low bloom hydrolyzed gelatin are added slowly withagitation to 610 kilograms of distilled water heated to 65°-75°C. Theagitation is continued for 2 hours with the slurry maintained at70°-80°C. Agitation is then stopped and the temperature is maintained at70°C. overnight to eliminate the air from the heavily foamed gelatinsolution.

The hot hydrolyzed gelatin stock solution is transferred to ahomogenizing kettle equipped with a Homo-Mixer. Rapid agitation is begunwith the Homo-Mixer and 152.2 kilograms of a flavor oil (e.g., orangeoil, grape flavor, pineapple flavor), previously heated to 40°-50°C., isslowly added and emulsified.

The emulsion is cycled through the sonic homogenizer to prepare anemulsion with suitable dispersed particle size, i.e., less than 1-3microns. The solids concentration is adjusted to insure proper sprayviscosity, i.e., about 180-200 centipoises per second, by the additionof sufficient distilled water. The emulsion is then passed through thesonic homogenizer into a suitable storage vessel.

The inlet temperature of a 14 foot Bowen Dryer is adjusted to 325°F. andthe outlet temperature adjusted to 200°-210°F. The system is balancedusing water after which the water is shut off and the flavoroil-hydrolyzed gelatin emulsion is fed to the Dryer. The atomizer wheelspeed positioned below the absorbent inlet is set initially at12,000-13,500 rpm and the flow rate of silicic acid absorbent-glidant,metered into the Dryer through a top inlet valve, is adjusted to providea glidant concentration approximately equal to 2% by weight of theconcentration of the spray-dried product. The atomizer wheel speed isthen adjusted downward to 8,000-9,000 rpm and, after 5 minutes, theDryer outlet temperature is adjusted to 195°-180°F. By theseadjustments, the emulsion feed rate is increased causing the spraydroplets to increase in size and agglomerate. The wet agglomerateparticles are coated with the glidant prior to impinging on the Dryerchamber wall. There is no adhesion and thus the thermoplastic particleshave a long drying period.

The resulting material is an agglomerated, free-flowing, flavor oilencapsulated powder having a bulk density of 35.4 pounds per cubic footand a moisture content of 1.5 to 2.5% by weight.

We claim:
 1. A spray-dried, free-flowing, non-dusting, static-freeriboflavin powder composition comprising, in percents by weight based onthe total weight of the powder, from about 45 to about 65% ofriboflavin, from about 15 to about 25% of oyster shell flour as anon-absorbent inorganic filler, from about 15 to about 35% of ahydrolyzed cereal flour and from about 1 to about 5% of silicic acid;said composition in the form of agglomerated particles having a bulkdensity of 35-36 pounds per cubic foot.